Effect of Nonlinear Modeling of Beam-Column Joint on Pushover Analysis

Abstract

The present paper is concerned with the seismic risk assessment of buildings in the Kingdom of Saudi Arabia. A critical review of the existing literature is presented to identify the shortcomings of extant studies. None of the extant studies considered nonlinear action of the beam-column joint (BCJ) but rather they dealt with BCJ as a rigid element for simplicity and the only plastic hinging has been considered in beams and/or columns. Hence the main focus of this paper is to demonstrate the significant effects of the nonlinear action of BCJ in the pushover analysis and in turn the inadequacy of all previous studies which overlooked such effect. In this study, nonlinear static pushover analysis is performed on two-dimensional RC frames of existing buildings in Jeddah city, with and without using macro node elements and pushover curves are compared. The beam-column joint modelling approach adopted in this study is through macro node element which accounts for failure due to shear collapse of the joint, concrete crushing, flexural and/or shear plastic damage of the beams or columns connected and bond-slip failure. The results clearly indicate that the RC frame in which the beam-column joints were modeled using a macro node element, tends to have lesser base shear values and higher displacement capacity when compared to the RC frame modeled without using the macro node. Furthermore, the status of plastic hinges developed in building frames modeled without using macro node element was found to be within the Immediate occupancy (IO) performance level, but this hinge status drastically changed to Collapse prevention (CP) performance level when BCJ was modeled using macro node. Hence, the results highlight that the nonlinear action of beam-column joint has a significant effect on the nonlinear response of a structure.